Ophthalmodynamometer

ABSTRACT

A portable ophthalmodynamometer, which operates in the active compression mode, includes a transparent plastic eyecup or speculum attached to a bellows-like bladder having glass endwalls. The eyecup fits under the eyelids and is seated against the sclera by a headstrap attached to the bladder structure and secured around the head. An integral adjustment gauge facilitates correct positioning of the ophthalmodynamometer on the eyeball. An air duct extends from the interior of the bladder structure to a hand squeeze bulb whereby manipulation of the bulb increases the internal pressure of the bladder structure. Increasing bladder pressure is transmitted to the eyeball via the eyecup to thereby raise intra-ocular pressure. Bladder pressure is related to retinal artery blood pressure. Means are provided to ascertain the bladder pressure so that retinal artery blood pressure may be determined.

United States Patent Chisum et al.

Sept. 9, 1975 OPHTHALMODYNAMOMETER Inventors: Gloria T. Chisum,Philadelphia;

John Nichparenko, Willow Grove, both of Pa.

The United States of America as represented by the Secretary of theNavy, Washington, DC.

May 1, 1974 U.S. Cl. 128/2 T; 73/80; 128/205 R;

Int. Cl. A6113 3/00; A61B 5/02 Field of Search.v 128/2 T, 2 R. 2.05 N.2.05 R.

References Cited UNITED STATES PATENTS Darnron 128/205 N Allen.....128/2 T X Gluzek 73/110 X Uemura et al. 128/2 T [73] Assignee:

[22] Filed:

[21] Appl. No.: 465,800

Hargcns 111 et a1. 73/80 Sisler 128/2 T Kanter et al. 128/2 T PrimaryE.\'umincrKyle L. Howell Almrm'y, Agwu, or FirmR. S. Sciascia; HenryHansen; R. J. Mooney l 57 1 ABSTRACT A portable ophthalmodynamometer.which operates in the active compression mode, includes a transparentplastic eyecup or speculum attached to a bellowslikc bladder havingglass endwalls. The eyecup fits under the eyelids and is seated againstthe sclera by a headstrap attached to the bladder structure and securedaround the head. An integral adjustment gauge facilitates correctpositioning of the ophthalmodynamometer on the eyeball. An air ductextends from the interior of the bladder structure to a hand squeezebulb whereby manipulation of the bulb increases the internal pressure ofthe bladder structure. lncreasing bladder pressure is transmitted to theeyeball via the cyecup to thereby raise intra-ocular pressure. Bladderpressure is related to retinal artery blood pressure. Means are providedto ascertain the bladder pressure so that retinal artery blood pressuremay be determined.

12 Claims, 4 Drawing Figures l|--4O 11 l I1 l I .2 U l 2 I L1 passsuasINDICATOR PATENTEDSEP 9 I925 PRESSURE lNDiCATOR OPHTHALMODYNAMOMETERSTATEMENT OF GOVERNMENT INTEREST The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

BACKGROUND OF THE INVENTION This invention relates toophthalmodynamometers and in particular to ophthalmodynamometers whichemploy the active compression principle.

An ophthalmodynamometer is an instrument which measures retinal arterypressures by applying a variable but calibrated force over a known areaof the eye to induce systole, i.e., pulsations at the peak of the bloodpr "sure cycle, and diastole, i.e., pulsations at the minimum of theblood pressure cycle, of the central retinal artery. With theophthalmodynamometer the intraocular pressure is artificially elevatedby means of mechanically applied pressure or suction. A separateapparatus, e.g., a hand held ophthalmoscope, is then employed to observeor detect the pulsations. (The essential function of the ophthalmoscopeis to provide illumination through the pupil of the eye so that theexaminer may view the fundus of the eye.) Measurement of retinal arterypressure can be used to detect several important body conditions, e.g.,increased intracranial pressure, partial or complete carotid arteryblockage, and carotid vascular blockage.

Present day ophthalmodynamometers increase intraocular pressure by usingeither a suction device or a compression device. The compression deviceemploys a small flat disc which is pressed against the sclera of the eyewith a calibrated force applicator. The suction device employs a smallcup and a calibrated vacuum device to apply suction to a portion of thesclera. The compression and suction ophthalmodynamometer devices bothdistort the globe of the eye. This distortion tends to raise thepressure of the relatively incompressible vitreous fluid within the eye.The increased pressure of the vitreous fluid is then exerted against thecentral retinal area of the eye.

Conventional ophthalmodynamometers have several drawbacks. In both thecompression type and the suction type, the actual increase inintra-ocular pressure is nonlinearly related to the external forceapplied to sclera. Hence it is difficult to establish an exactrelationship between the force applied to the sclera and the actualretinal artery pressure. In the compression type, the axis of pressureapplication is sometimes nonnormal to the sclera giving rise to lateralforces which can cause slippage of the disc on the sclera. In thesuction type, measurement errors are sometimes introduced when there isa partial loss of vacuum around the periphery of the suction cup or thepneumatic tube providing the vacuum partially collapses. Both types ofconventional ophthalmodynamometers are uncomfortable for the patient,difficult to properly and conveniently employ and generally giveuncertain results. In addition, conventional ophthalmodynamometerscannot be used under field or combat conditions since they employcumbersome equipment and normally require the patient to be in a uprightposition.

SUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide a compression ophthalmodynamometer which is convenient toemploy and which reliably determines retinal artery pressure withoutunduly discomfiting the patient. It is a further object of thisinvention to provide an ophthalmodynamometer which is portable,atraumatic to the eye, and which can be used under field or combatconditions even where the patient is in a prone position. These andother objects of the invention are achieved as follows:

A portable ophthalmodynamometer, which operates in an active compressionmode, is provided with a transparent plastic eyecup and a fluidimpermeable bladder structure. The bladder structure is substantiallycylindrical with glass endwalls and a sidewall fabricated from a pleatedbut distensible material. The eyecup is removably secured to the bladderstructure by means of a grooved retaining clip. A fixed lengthattachment gauge secured to the retaining clip ensures correct seatingof the eyecup on the sclera. An air duct extends from the interior ofthe bladder structure to a squeeze bulb and pressure indicator means.After the ophthalmodynamometer has been properly placed on the eyeballwith the aid of head straps the bladder structure is pressurized bymeans of the squeeze bulb. As the bladder pressure increases a force istransmitted to the sclera via the eyecup and the intra-ocular pressureis thereby increased. With an ophthalmoscope, systole and diastole areobserved and the corresponding bladder pressure is ascertained from thepressure indicator means. Since internal bladder pressure is related tointra-ocular pressure, a measurement of retinal artery pressure isobtained.

Other objects, advantages, and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. la shows an ophthalmodynamometeraccording to the invention partially in section;

FIG. lb shows an end view of the ophthalmodynamometer of FIG. 1', and

FIG. 2 shows a modification of a portion of the ophthalmodynamometershown in FIG. 1; and

FIG. 3 shows the ophthalmodynamometer of the present inventionpositioned on the eye and held in place with a head strap.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. la theophthalmodynamometer 10 of the present invention includes a transparentplastic eyecup or speculum 12 attached to a bladder I4 having abellows-like structure. The eyecup 12 has a flared or virtuallysemi-spherical portion which fits under the eyelids (not shown) andrests against the sclera 31 just outside the periphery of the cornea 33.The flared portion 12a tapers to a viewing port or orifice 12b having acircumference slightly larger than a cornea. (The flared portion 12aprevents the eyelids from closing when the ophthalmodynamometer is usedand also exerts pressure on the sclera as will be described more fullyhereinbelow). Thereafter the eyecup 12 extends as a substantiallyfrusto-conical portion 12c having a planar rim 12d which isremovablyretained within a circular groove provided on a plastic retaining clipor keeper 13. (A suitable eyecup 12 that may be used in the presentinvention may be the eyecup employed to hold the Burian Allen ERGElectrode manufactured by the Hansen Ophthalmodynamometer DevelopmentLaboratory of Iowa City. Iowa). The sidewall l4c of the bladderstructure 14 is fabricated from any suitable material which is bothdistensible and fluid impermeable such as silicone rubber. The bladder14 is generally cylindrical in form and has a sidewall l4c constructedin a pleated or corrugated fashion much like a bellows. Both endwallsMa. 14!: ofthc bladder 14 are fabricated from anti-reflection coatedglass or scratch resistant plastic formed in the shape of a disc.

One endwall 14b of the bladder structure I4 is provided with a plasticcircular mounting ring 16 having head strap lugs 32. 32' as can be seenbest in FIG. lb. The circular ring 16 occupies the outer periphery ofthe glass endwall 14b and is attached thereto by an adhesive such aspermaband 101 contact cement or any other suitable means. The circularring 16 has a thickness sufficient to provide a secure base or supportfor head strap lugs 32. 32'. A head strap 38 is attached to each headstrap lug 32. 32' and brought behind the paticnt's head where it can beincrementally tightened.

A second endwall I41: of the bladder structure 14 is provided with agrooved circular retaining clip or keeper [3 which is securely attachedto the glass endwall 140 by an adhesive such a permaband I01 contactcement or any other suitable means. The plastic retaining clip or keeperl3 occupies the outer periphery of glass l4u and is used to removablysecure the speculum or eye cup 12 to the bladder structure l4 by meansof a groove I311.

A fixed length plastic adjustment gauge 30 is attached to the retainingclip 13 and extends above and along the upper portion of the bladderstructure 14. The gauge 30 is slightly smaller than the undistendedlength of the bladder structure 14; within this constraint the exactlength of the adjustment gauge is not critical but its optimum lengthwill depend on the actual dimensions of a finally and fully fabricatedophthalmodynamometer 10. The gauge 30 is used by the examiner toproperly position the ophthalmodynamometer on the patients eye as willbe explained more fully hereinbelow. A duct 18, of any suitablematerial. extends through the lower portion of ring 16 to at least theinterior surface of the glass endwall 14b. The duct I8 is suitablyconnected to a pneumatic tube 20 which extends to a normally closedexhaust valve 24 and a squeeze-bulb 26 such as those used with aconventional cuff-type sphygmomanometer. (To those skilled in the artthe exhaust valve 14 is also known as sphygmomanometer inflation bulb).The exhaust valve 24 and squeeze-bulb 26 are shunted by a conventionalpressure indicator 22 which transduces applied pressures to a readablenumerical value.

Referring to FIGS. l and 3, the operation of the ophthalmodynamometer 10is as follows. The ophthalmodynamometer I0 is placed on the eyeball sothat the eyecup 12 fits under the eyelids and rests against the sclera31 just outside the periphery of the cornea 33. The Headstraps 38 (FIGv3) attached to the lugs 32 and 32' on the mounting ring 16 are broughtbehind the patients head and thereafter incrementally tightened. Thehead straps 38 are tightened only until the outer surface of the ring 16is aligned with the distal end a of the adjustment gauge 30 as shown inFIG. 3. When such alignment occurs the eyecup 12 is correctly seated onthe sclera 30 and presses against the sclera with enough force tominimize slippage but not enough force to introduce a significantpressure increment to the eyeball prior to pressurization of the bladderstructure.

After the ophthalmodynamometer has been posi tioned on the eyeball. thepressure within the bladder structure 14 is increased by squeezing bulb26. As the pressure increases. the bladder structure tends to distendand exerts a pressure against the eyeball via the cyecup 12. With anopthalmoscope 40 the examiner views the fundus 34 of the eye andcontinues to increase the pressure until he observes the characteristiccollapse of the retinal artery. Thereafter the exhaust valve 24 isopened and the pressure decreases. As the pressure decreases theexaminer observes the characteristic first blood pulse at the high pointof the blood pressure cycle. i.e.. systole. As the pressure continues todecrease, the examiner notes the last blood pulse at the low point ofthe blood pressure cycle. i.e., diastole. The corresponding readingsfrom pressure indicator 22 represent the retinal artery blood pressureat systole and diastole respectively.

It is apparent from the description of the ophthalmodynamometersoperation set forth above. that it operates in an active compressionmode as opposed to a passive compression mode. In the active mode, thebladder sructure 14 is in a semi-flaccid or substantially undistendedstate when the ophthalmodynamometer is initially positioned on theeyeball. Thereafter, the blad der structure 14 is pressurized bysqueeze-bulb 26 and caused to expand or distend to thereby transmit anincreased pressure to the eyeball via the eyecup 12. If theophthalmodynamometer 10 were operated in a passive mode. there would beno need for the squeezebulb 26 and the exhaust valve 24. That is. thebladder structure 14 is pressurized before it is placed on the eyeballand the internal pressure of the bladder structure 14 is in creased byexerting an internal force against an endwall of the bladder structure14 after the ophthalmodynamometer is positioned on the eyeball. Theincreased internal pressure within the bladder structure 14 under theinfluence of the external force is registered on the pressure indicator22.

Referring to FIG. 2, wherein like numerals refer to parts alreadyillustrated, a modification of the bladder structure shown in FIG. la isportrayed. The single walled bladder structure 14 of FIG. 1 is replacedby a double walled bladder structure 14' shaped substantially in theform of a toroid having pleated or corrugated sidewalls l4a' and 14bmuch like a bellows. The entire double walled bladder l 1 maybefabricated from a fluid impermeable but distensible material such assilicone rubber. The double walled bladder 14' is secured to the eyecup12 by an adhesive such as permabond 101 contact cement or by any othersuitable means at endwall 14c". And air duct 18' extends from theinterior of the double walled bladder to the parallel connected pressureindicator 22, exhaust valve 24 and squeeze bulb 26 as before. Anadvantage of the double walled bladder structure 14' over the singlewalled structure is that glass endwalls are made unnecessary since thefundus 34 may be observed through the toroid hole 14d. Operation of anophthalmodynamometer equipped with the double walled bladder 14' is thesame as that set forth hereinabove for the single walled bladderstructure 14.

()b\iously. many modifications and variations of the present in\cntionare possible in the light of the above teachings. It is therefore to beunderstood that within the scope ofthe appended claims the invention maybe practiced otherwise than as specifically described.

We claim:

1. An ophthalmodynamometer comprsiing:

a speculum member ha ing an opening formed by two oppositely flaringsurfaces ofreyolution. one of said surfaces being formed to fit againstthe sclera of the eye beneath the upper and lower eyelids;

a bladder member attached to the other of said surfaces for transmittinga force to said speculum member. said bladder member having a transparent portion concentric v ith said speculum opening;

first means attached to said bladder member for securing said onesurface against the selera;

second means operatively connected to said bladder member for varyingthe internal pressure of said bladder member; and

third means operatiwly connected to said bladder member for monitoringthe internal pressure of said bladder member.

2. An ophthalmodynamometer according to claim l wherein said bladdermember includes:

further including:

at least one head strap;

means attached to said first endwall for securing said head strap tosaid bladder member;

an ad ustment gage;

retaining means attached to said second endwall for securing saidadiustment gage to said bladder mem her. said retaining means includingmeans integral therewith for securing said speculum member to saidbladder member.

4. An ophthalmodynamometer comprising:

a substantially cylindrical bladder having a pleated sidewall attachedto first and second transparent disc shaped endwalls;

a keeper attached to said first endwall'.

a mounting ring attached to said second endwall:

an eyecup member attached to said keeper, said eyecup member having aviewing port concentric with said transparent disc-shaped cndwalls;

an adjustment gauge attached to said keeper; and

a tube having a first end portion extending through said mounting ringand said second endwall. and a second end portion serially connected toa normally closed exhaust valve. a squeeze bulb and a pressure indicatormeans connected in parallel with respect to each other.

5. An ophthalmodynamometer comprising:

first means for applying force over a predetermined area of an eyeball:

III

wherein said bladder member includes:

a hollow substantially cylindrical bladder having a corrugated sidewallattached to first and second transparent disc shaped endwalls;

a mounting ring attached to said first endwall and having at least onehead strap lug thereon for re' ceiving said head strap; and

a keeper attached to said endwall for supporting said adjustment gage.said keeper including attachment means integral therewith for securingsaid first means to said keeper.

7. An ophthalmodynamometer according to clain 6 herein said second meanscomprsies:

a tube member extending from the interior of said hollow cylindricalbladder through said first trans-- parent endwall and said mounting ringto a squeeze bulb shunted by a normally closed exhaust valve.

8. An ophthalmodynamometer according to claim 7 wherein said third meanscomprises:

a pressure indicator shunt connected to said tube member. 9. Anophthalmodynamometer according to claim 8 wherein said first meanscomprises a transparent eyecup having:

a flared portion shaped to subatantially conform to the contour of asclera and operative to prevent eyelid closure as well as exert forceagainst the sclera; and

a frusto-conical portion terminating in a planar rim;

wherein said fursto-conical portion and said flared portion abut attheir respective smallest diameters to form a viewing port having adiameter slightly larger than a cornea.

[0. An ophthalmodynamometer according to claim 9 wherein said discshaped endwalls and said viewing port are concentrici ll. Anophthalmodynamometer according to claim 10 wherein said bladder issubstantially composed of a fluid impermeable, distensible material.

12. An ophthalmodynamometcr according to claim 11 wherein said materialis silicone rubber.

1. An ophthalmodynamometer comprsiing: a speculum member having anopening formed by two oppositely flaring surfaces of revolution, one ofsaid surfaces being formed to fit against the sclera of thE eye beneaththe upper and lower eyelids; a bladder member attached to the other ofsaid surfaces for transmitting a force to said speculum member, saidbladder member having a transparent portion concentric with saidspeculum opening; first means attached to said bladder member forsecuring said one surface against the sclera; second means operativelyconnected to said bladder member for varying the internal pressure ofsaid bladder member; and third means operatively connected to saidbladder member for monitoring the internal pressure of said bladdermember.
 2. An ophthalmodynamometer according to claim 1 wherein saidbladder member includes: a closed tube having a corrugated sidewallattached to first and second transparent endwalls.
 3. Anophthalmodynamometer according to claim 2 further including: at leastone head strap; means attached to said first endwall for securing saidhead strap to said bladder member; an adjustment gage; retaining meansattached to said second endwall for securing said adjustment gage tosaid bladder member, said retaining means including means integraltherewith for securing said speculum member to said bladder member. 4.An ophthalmodynamometer comprising: a substantially cylindrical bladderhaving a pleated sidewall attached to first and second transparentdisc-shaped endwalls; a keeper attached to said first endwall; amounting ring attached to said second endwall; an eyecup member attachedto said keeper, said eyecup member having a viewing port concentric withsaid transparent disc-shaped endwalls; an adjustment gauge attached tosaid keeper; and a tube having a first end portion extending throughsaid mounting ring and said second endwall, and a second end portionserially connected to a normally closed exhaust valve, a squeeze bulband a pressure indicator means connected in parallel with respect toeach other.
 5. An ophthalmodynamometer comprising: first means forapplying force over a predetermined area of an eyeball; a bladder memberattached to said first means, said bladder member having a transparentportion through which said eyeball may be observed; second meansoperatively connected to said bladder member for varying the internalpressure of said bladder member; third means operatively connected tosaid bladder member for monitoring the internal pressure of said bladdermember; at least one head strap attached to said bladder member; and anadjustment gage attached to said bladder member.
 6. Anophthalmodynamometer according to claim 5 wherein said bladder memberincludes: a hollow substantially cylindrical bladder having a corrugatedsidewall attached to first and second transparent disc shaped endwalls;a mounting ring attached to said first endwall and having at least onehead strap lug thereon for receiving said head strap; and a keeperattached to said endwall for supporting said adjustment gage, saidkeeper including attachment means integral therewith for securing saidfirst means to said keeper.
 7. An ophthalmodynamometer according toclain 6 wherein said second means comprsies: a tube member extendingfrom the interior of said hollow cylindrical bladder through said firsttransparent endwall and said mounting ring to a squeeze bulb shunted bya normally closed exhaust valve.
 8. An ophthalmodynamometer according toclaim 7 wherein said third means comprises: a pressure indicator shuntconnected to said tube member.
 9. An ophthalmodynamometer according toclaim 8 wherein said first means comprises a transparent eyecup having:a flared portion shaped to subatantially conform to the contour of asclera and operative to prevent eyelid closure as well as exert forceagainst the sclera; and a frusto-conical portion terminating in a planarrim; wherein said fursto-conical portion and said flared portion abut attheir respective smallest diameterS to form a viewing port having adiameter slightly larger than a cornea.
 10. An ophthalmodynamometeraccording to claim 9 wherein said disc shaped endwalls and said viewingport are concentric.
 11. An ophthalmodynamometer according to claim 10wherein said bladder is substantially composed of a fluid impermeable,distensible material.
 12. An ophthalmodynamometer according to claim 11wherein said material is silicone rubber.